Method and System for Customizable Flow Management in a Cellular Basestation

ABSTRACT

A method for customizable flow management in a cellular basestation including configuring a framework on a cellular basestation; and executing customized flow management functions through the framework by an external entity.

This application claims the benefit of U.S. Provisional Application No.61/309,110, entitled “NVS: A Virtualization Substrate for WiMaxNetworks”, filed Mar. 1, 2010, and is related to U.S. patent applicationSer. No. 13/037,442, entitled “METHOD AND SYSTEM FOR VIRTUALIZING ACELLULAR BASESTATION”, filed Mar. 1, 2011, both of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to wireless communications andmore particularly to a method and system for customizable flowmanagement in a cellular basestation.

Mobile virtual network operators MVNOs are emerging as strong players inthe mobile network market to provide enhanced services such as videotelephony, live streaming and interactive games (along with traditionalvoice services) to focused customers. This model is argued to be awin-win situation for both MVNOs and mobile network operators MNOs,since MVNOs help MNOs attract and retain a greater number of customers.For MNOs and MVNOs, customizability fosters greater innovation in flowmanagement and other services to achieve differentiation from theircompetitors (100 and 102). For controlled evaluation of innovations(101), greater customizability would enable deploying and testing newsolutions without recompiling or rebooting the basestations. Inaddition, most basestation manufacturers restrict access to thebasestations they provide to the MNOs. Customization would provide MNOswith more access to the flow management with little modification to thebasestation. The MNOs can pass this functionality to the different MVNOsit hosts.

As revenue from voice services is decreasing rapidly, data services arereceiving increased focus from WiMAX, 3G and LTE network operators.Already, more sophisticated data plans for revenue generation on 3Gnetworks have emerged, and are constantly evolving. Many of thesesophisticated data plans include corporate bundle plans where thebandwidth is shared across a group of employees of a corporation. Themanagement policies of flows/group of flows for a corporation or anenterprise have unique requirements. A network with customized flowmanagement would be an ideal fit for enterprises offering wirelessservices to its employees. Further corporate intranets can be madeaccessible to users “everywhere” through complete virtualization of thenetwork resources (101).

The goal of the global environment for network innovations GENI is toenable a general virtualized environment for supporting experimentationand prototype deployments for studying innovative technologies inlarge-scale real life scenarios (101). This has not been possible in thepast since mobile network operator MNO equipment has been closed forexperimentation. Customization can help MNOs to provide a way to deployand test innovative ideas, while running operational networks. Thisprovides a win-win situation for both network providers and researchers.

Currently, there are no teachings on providing customizability oncellular wireless basestations over technologies such as WiMAX and LTE.Many researchers rely on simulations to evaluate new schedulingprocesses, but simulations are ineffective in modeling the differentreal-world scenarios. Moreover, no prior scheduling discipline allowedexecution of customized flow management by an outside entity on awireless basestation. MNOs and MVNOs have relied on the efficiency ofthe flow management implemented in the basestations by the basestationequipment manufacturers.

Accordingly, there is a need for customizable and adaptiveflow-management that provides an interface for flow management incellular basestations such as WiMAX and LTE.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides a method for customizable flowmanagement in a cellular basestation including configuring a frameworkon a cellular basestation; and executing customized flow managementfunctions through the framework by an external entity.

In the preferred embodiment, the framework includes programminginterfaces for enabling at least one of a selection and definition ofdistinct means for specifying flow management functions and the flowmanagement functions include at least one of a virtual time tagging, ascheduler selection and a model specification. Preferably, for thevirtual time tagging the entity marks packets with a virtual time thatdetermines the order in which packets are transmitted, the basestationsends packets in the order of the virtual time tags embedded in eachpacket and the entity marks packets based on feedback from thebasestation. Preferably, for the model specification the basestationallows the entity to specify at least one of a function and apre-computed table of parameters to weight combinations that enables thebasestation to determine weights dynamically, with the weights beingused to define an order of packet transmissions. Preferably, for thescheduler selection a specific flow management function is chosen from apre-defined set of functions already implemented within the basestation.Preferably, the customized flow management functions include at leastone of being implemented either outside or inside the basestation andchanged dynamically by the entity at run-time. An example of beingoutside the basestation includes a loadable module and being inside thebasestation includes a virtual machine.

The present invention generally provides for a cellular basestationconfigured with flow management including means configuring a frameworkon a cellular basestation; and means for executing customized flowmanagement functions through the framework by an external entity.

These and other advantages of the invention will be apparent to those ofordinary skill in the art by reference to the following detaileddescription and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is depicts exemplary deployment scenarios that benefit fromcustomizable and adaptive low management in accordance with theinvention: (a) Virtualization across Users 100; (b) CompleteVirtualization 101; and (c) Virtualization across Services 102;

FIG. 2 is an exemplary diagram of a customizable and adaptive flowmanagement emulator, in accordance with the invention; and

FIG. 3 is a diagram steps for computing flow and weight for a MAC frame,in accordance with the invention.

DETAILED DESCRIPTION

The present invention is directed to a customizable and adaptiveflow-management emulator (CAFE) that provides an interface for flowmanagement in cellular basestations such as WiMAX and LTE. The inventiveCAFE enables deploying different custom flow management schedulersdesigned for diverse performance objectives on the same basestation.

The inventive CAFE provides a generic framework that enables entities,either from within the basestation or outside the basestation, todynamically configure and execute custom flow management. CAFE definesseveral interfaces/APIs that allow entities to configure the basestationin distinct ways. These different approaches ensure that the samebasestation design can meet the requirements of a broader class ofentities. Entities could refer to MNOs, MVNOs, Corporate/enterprisenetworks, and Experimenters/researchers. Entities may execute outsidethe physical boundaries of the basestation or within thebasestation(e.g., As a Virtual Machine inside the basestation).

Referring now to FIG. 2, there is shown a block diagram of the inventiveCAFÉ that is a flow management emulation framework that is preferablyimplemented as part of a cellular basestation. The inventive CAFEincludes a flow management emulator 111, a function selection 112, amodel specification 113, a model specification 113, a per-flow feedback114, and a virtual time tagging 115.

The flow management emulator 111 enables the CAFE to provide programminginterfaces to let an entity determine the order in which packets of thedifferent flows are to be transmitted. For maximum flexibility andefficiency, the resources have to be allocated at fine timescales suchas on a per-packet or per-MAC-frame basis.

Three approaches are defined in CAFE for giving entities the flexibilityto specify flow scheduling that has different merits and demerits:function selection 112, model specification 113, and virtual timetagging 114.

With the Function Selection 112 approach, the inventive CAFE provides avariety of commonly employed schedulers that an entity can choose from.This approach may be very attractive to entities like MVNOs, corporatenetworks, or service providers with no expertise in wireless networkingand prefer relying on the basestation to take care of flow management.This approach, however, is not suitable for evaluating new innovations.

With the Model Specification 113 approach, the inventive CAFE provides aprogramming interface to specify on a per-class or per-flow basis, theweight distribution as a function of the average rate already achieved,modulation and coding scheme, packet loss, the flow's minimum reservedrate and maximum sustained rate. The weight distribution is sent as aset of discrete tuples that are stored in a table in the basestationthat CAFE looks-up during flow scheduling. CAFE emulates flow schedulingby choosing the flow(s) in the decreasing order of the weights. Forflows with the same weight, CAFE chooses the flow with lower averagerate achieved. This approach is general in that a large number of flowschedulers such as RR, WRR and proportional fair, can be specified as aset of discrete tables. However, this approach has a drawback; flowmanagement functions for which the set of weights cannot be representedoffline and/or depends on online information such as current allocationof other flows, current channel conditions, etc. cannot be emulated bythis approach.

With the per-flow feedback 114 approach, the inventive CAFE providesflow-level feedback to the entity to perform flow scheduling itself, andplace a tag on each packet of the flow with a virtual time thatmonotonically increases. The per-flow feedback includes average rateachieved, packet loss, MCS etc. In this case, CAFE picks from the flows,the packet among all packets at the heads of the flow queues that hasthe least virtual time. While this approach enables arbitrary flowschedulers to be defined, the drawback of this approach is that thefeedback interval impacts the scheduling decisions and may require theentity to be as close to the basestation as possible. Both ModelSpecification and Virtual Time Tagging may execute within thebasestation as Virtual Machines or loadable modules or external entitiessuch as gateways or routers (e.g., ASN gateway or CSN for WiMAX).

When using the Virtual Time Tagging 115 approach for the CAFE, theentity needs to take care of flow scheduling and tagging each packetwith the correct virtual time so that CAFE sends out the packets in thedesired order. The flow scheduler in the entity makes use of theper-flow feedback from the basestation in order to schedule the order ofthe packets.

Henceforth, we describe the core engine behind CAFE using an example ofa CAFE implementation shown in FIG. 3. For choosing a flow, CAFE may usethe following specific method: For each MAC frame, select a flow withthe maximum weight. Repeat this until the MAC frame is completely filledup or all flows are satisfied 210, FIG. 3 (a).

PROCflow_sched compute_wts( ) WHILE space availin MAC frame selectpktfrom flows i with maximum w_i END WHILE update avgRate for all flows

Depending on the choice of the approach to be used in the inventiveCAFE, the model specification weight calculation 211 or virtual timetagging weight calculation 212 are employed to compute the weight ofeach flow.

For each MAC frame, select flow with the maximum weight. Repeat thisuntil the MAC frame is completely filled up or all flows are satisfied.Depending on the choice of the approach to be used in CAFE, the modelspecification or virtual tagging are employed to compute the weight ofeach flow, 1. w_j=Table [i][avgRate][MCS], 211, 1.w_j=−(head_queue_tag(i)), 212 respectively in FIG. 3, (b).

Alternatively, even fine-grained customization can be achieved (withincreased run-time overhead) by executing compute_wts( ) and updateavgRate within the WHILE; ie. Weight re-evaluation is done on aper-packet basis.

With the model specification weight calculation 211 the weight of a flowis computed from the weight distribution provided to the CAFE. Theweight distribution of each flow is provided as a table of weights fordifferent values of average rate, MCS and/or packet loss.

With the virtual time tagging weight calculation 212 the weight is avalue directly mapped from the virtual time tag of the packet at thehead of the line of each queue. The entity has to mark each packet withan explicit tag to ensure the order of packet transmission ismaintained.

Among the innovations of the inventive CAFE are the design and executionof the flow management emulator 111. The function selection 112, modelspecification 113 and per-flow feedback 114 are required to support theflow management emulator 111 with three different approaches. Theinventive architecture to enable custom flow schedulers supportsmultiple customized, programmable and dynamicallyinstallable/configurable flow management functions. The three approaches1112-114 enable dynamically configuring the custom flow managementfunction by an entity present within the basestation or outside it.

Among many advantages with the invention, the inventive CAFE allowsbasestation providers to realize a programmable basestation for flowmanagement without giving complete information about the design of thebasestation. The inventive CAFE allows network providers, virtualnetwork providers and service providers to run custom resourcemanagement functions from within or outside the basestations easily, afeature non-existent today. The CAFE also removes the requirement ofre-compilation/re-powering/re-booting of the basestation for enablingnew flow management customizations.

The combination of the inventive flow management emulator 111, thefunction selection 112, the model specification 113 and the per-flowfeedback 114 lead to at least the following advantages: 1) an ability tocreate, modify and execute arbitrary flow management algorithms on anotherwise closed basestation; 2) new business models such as MVNOs,corporate networks having more control over their flow management, and(3) better management through ease of programmability, and incrementalinnovation and evolution of basestations.

The foregoing Detailed Description is to be understood as being in everyrespect illustrative and exemplary, but not restrictive, and the scopeof the invention disclosed herein is not to be determined from theDetailed Description, but rather from the claims as interpretedaccording to the full breadth permitted by the patent laws. It is to beunderstood that the embodiments shown and described herein are onlyillustrative of the principles of the present invention and that thoseskilled in the art may implement various modifications without departingfrom the scope and spirit of the invention. Those skilled in the artcould implement various other feature combinations without departingfrom the scope and spirit of the invention.

1. A method for customizable flow management in a cellular basestation comprising the steps of: configuring a framework on a cellular basestation; and executing customized flow management functions through the framework by an external entity.
 2. The method of claim 1, wherein the framework comprises programming interfaces for enabling at least one of a selection and definition of distinct means for specifying flow management functions.
 3. The method of claim 2, wherein the flow management functions comprise at least one of a virtual time tagging, a scheduler selection and a model specification.
 4. The method of claim 3, wherein for the virtual time tagging the entity marks packets with a virtual time that determines the order in which packets are transmitted.
 5. The method of claim 3, wherein for the virtual time tagging the basestation sends packets in the order of the virtual time tags embedded in each packet.
 6. The method of claim 3, wherein for the virtual time tagging the entity marks packets based on feedback from the basestation.
 7. The method of claim 3, wherein for the model specification the basestation allows the entity to specify at least one of a function and a pre-computed table of parameters to weight combinations that enables the basestation to determine weights dynamically, with the weights being used to define an order of packet transmissions.
 8. The method of claim 3, wherein for the scheduler selection a specific flow management function is chosen from a pre-defined set of functions already implemented within the basestation.
 9. The method of claim 1, wherein the customized flow management functions comprise at least one of being implemented either outside or inside the basestation and changed dynamically by the entity at run-time.
 10. The method of claim 9, wherein said being outside comprises a loadable module or a virtual machine on an external gateway and said being inside comprises a loadable module or a virtual machine with said basestation.
 11. A cellular basestation configured with flow management comprising: means configuring a framework on a cellular basestation; and means for executing customized flow management functions through the framework by an external entity.
 12. The cellular basestation of claim 11, wherein the framework comprises means for programming interfaces for enabling at least one of a selection and definition of distinct means for specifying flow management functions.
 13. The cellular basestation of claim 12, wherein the flow management functions comprises means for at least one of a virtual time tagging, a scheduler selection and a model specification.
 14. The cellular basestation of claim 13, wherein for the virtual time tagging the entity marks packets with a virtual time that determines the order in which the packets are transmitted.
 15. The cellular basestation of claim 13, wherein for the virtual time tagging the basestation sends packets in the order of the virtual time tags embedded in each packet.
 16. The cellular basestation of claim 13, wherein, for the virtual time tagging, the entity marks packets based on feedback from the basestation.
 17. The cellular basestation of claim 13, wherein for the model specification the basestation allows the entity to specify at least one of a function and a pre-computed table of parameters to weight combinations that enables the basestation to determine weights dynamically, with the weights being used to define an order of packet transmissions.
 18. The cellular basestation of claim 13, wherein, for the scheduler selection, a specific flow management function is chosen from a pre-defined set of functions already implemented within the basestation.
 19. The cellular basestation of claim 11, wherein the customized flow management functions comprise at least one of being implemented either outside or inside the basestation and changed dynamically by the entity at run-time. 